import 'package:sqflite/sqflite.dart';

/// 數(shù)據(jù)庫幫助類
class DbHelper {

  final String path = "laoli.db"; // 數(shù)據(jù)庫名稱 一般不變
 //數(shù)據(jù)庫中的表名字 這里是我存錯(cuò)歷史搜索記錄的表
  static final searchTab = "SearchHistory";
   //私有構(gòu)造
  DbHelper._();
  static DbHelper? _instance;
  static DbHelper get instance => _getInstance();
  factory DbHelper() {
    return instance;
  }
  static DbHelper _getInstance() {
    if (_instance == null) {
      _instance = DbHelper._();
    }
    return _instance ?? DbHelper._();
  }

/// 數(shù)據(jù)庫默認(rèn)存儲(chǔ)的路徑
  /// SQLite 數(shù)據(jù)庫是文件系統(tǒng)中由路徑標(biāo)識(shí)的文件。如果是relative，
  /// 這個(gè)路徑是相對(duì)于 獲取的路徑getDatabasesPath()，
  /// Android默認(rèn)的數(shù)據(jù)庫目錄，
  /// iOS/MacOS的documents目錄。

  Future<Database>? _db;

  Future<Database>? getDb() {
    _db ??= _initDb();
    return _db;
  }

  // Guaranteed to be called only once.保證只調(diào)用一次
  Future<Database> _initDb() async {
  // 這里是我們真正創(chuàng)建數(shù)據(jù)庫的地方 vserion代表數(shù)據(jù)庫的版本，如果版本改變
  //，則db會(huì)調(diào)用onUpgrade方法進(jìn)行更新操作
    final db =
        await openDatabase(this.path, version: 1, onCreate: (db, version) {
      // 數(shù)據(jù)庫創(chuàng)建完成
      // 創(chuàng)建表 一個(gè)自增id 一個(gè)text
db.execute("create table $searchTab (id integer primary key autoincrement, name text not null)");      
    }, onUpgrade: (db, oldV, newV) {
      // 升級(jí)數(shù)據(jù)庫調(diào)用 
    ///  db 數(shù)據(jù)庫
   ///   oldV 舊版本號(hào)
   //   newV 新版本號(hào)
   //   升級(jí)完成就不會(huì)在調(diào)用這個(gè)方法了
    });

return db;
  }

// 關(guān)閉數(shù)據(jù)庫
  close() async {
    await _db?.then((value) => value.close());
  }
}

/// 數(shù)據(jù)操作類
class DbSearchHistoryDao {
  /// 增
  static insert(String text) {
    // 去重
    queryAll().then((value) {
      bool isAdd = true;
      for (var data in value) {
        if (data.name == text) {
          isAdd = false;
          break;
        }
      }
      if (isAdd) {
        DbHelper.instance.getDb()?.then((value) => value.insert(
              DbHelper.searchTab,
              DbSearchHotBean(name: text).toJson(),
            ));
      }
    });
  }

  /// 刪 全部
  static deleteAll() {
    DbHelper.instance.getDb()?.then((value) => value.delete(
          DbHelper.searchTab,
        ));
  }

  /// 更新數(shù)據(jù) 通過id更新表內(nèi)具體行的數(shù)據(jù)
  static update(DbSearchHotBean dbSearchHotBean) {
    DbHelper.instance.getDb()?.then((value) => value.update(
      DbHelper.searchTab,
      dbSearchHotBean.toJson(),//具體更新的數(shù)據(jù)
      where: "id = ?"http://通過id查找需要更新的數(shù)據(jù)
      ,whereArgs: [dbSearchHotBean.id]
    ));
  }

  /// 通過name查具體的實(shí)體類
  static Future<DbSearchHotBean?> getBean(String name) async {
  var db = await DbHelper.instance.getDb();
  var maps = await db?.query(DbHelper.searchTab,
    columns: ['id','name'],// 獲取實(shí)體類的哪些字段 默認(rèn)全部
    where: 'name = ?',//通過實(shí)體類中的name字段
    whereArgs: [name]);//具體name的值 限定數(shù)據(jù)
  if(maps!=null && maps.length > 0) {
       return DbSearchHotBean.fromJson(maps.first);
  }
  return null;
  }

  /// 查 全部all
  static Future<List<DbSearchHotBean>> queryAll() async {
    List<DbSearchHotBean> list = [];
    await DbHelper.instance
        .getDb()
        ?.then((db) => db.query(DbHelper.searchTab).then((value) {
              for (var data in value) {
                list.add(DbSearchHotBean.fromJson(data));
              }
            }));
    return list;
  }
}

class DbSearchHotBean {
  int? id;
  String? name; // 搜索詞

  DbSearchHotBean({this.id,required this.name});

  DbSearchHotBean.fromJson(Map<String, dynamic> json) {
    id = json['id'];
    name = json['name'];
  }

  Map<String, String?> toJson() {
    var map = <String, String?>{};
    map['id'] = id?.toString() ;
    map['name'] = name ?? "";

    return map;
  }
}

DbSearchHistoryDao.getBean("水").then((value){
  if(value!=null){
    DbSearchHistoryDao.update(DbSearchHotBean(id: value.id,name: "火"));
  }
});

batch = db.batch();
batch.insert('Test', {'name': 'item'});
batch.update('Test', {'name': 'new_item'}, where: 'name = ?', whereArgs: ['item']);
batch.delete('Test', where: 'name = ?', whereArgs: ['item']);
results = await batch.commit();